Ophthalmic products are available for treatment of various conditions. For example, the treatment of glaucoma requires frequent daily administrations of certain ophthalmic compositions having the desired pressure-relieving action. Ophthalmic fluids also are used to relieve eye strain and irritation caused by smog, allergens such as pollen and dust, smoking, and swimming, etc. In the application of certain medical preparations, it is necessary that the fluid be delivered in a fairly well-defined volume since an excessive dosage may result in improper physiological effects. Another requirement is that the need to properly target the dose of ophthalmic medication. A contributing factor in requiring the delivery of a specified dose is the matter of cost in the case of expensive medications. Many ophthalmic fluids may be self-administered by the user. Accordingly in the case of self-treatment, a further consideration is the need to achieve delivery to the targeted eye without the patient having to assume a strained body, head or hand position, since such a strained posture may result in forced errors. Another important factor to consider in facilitating patient self-treatment and operator-assisted treatment is that ophthalmic medications are commonly sold in small bottles which are not designed to function as controlled dosage applicators. Therefore there is a need for dispenser/applicator device that is adapted to accept conventional ophthalmic product bottles, with the containers being easy to install and replace, and with the device filling control being unaffected by the size of the ophthalmic product container. An important consideration in using an applicator device to administer ophthalmic products to the eye is the need to maintain a sterile condition in the applicator.
A number of different applicator devices are known for dispensing an ophthalmic product to the eye of a patient. Such known devices suffer from various limitations. Certain devices for small volumes are based either on drop or on spray delivery principals. Drop applicators rely on impact by gravity, but common designs give little control over the administration of ophthalmic products. Certain devices are difficult to operate except with proper orientation of the device. Spray applicators rely on a shower. While prior spray applicators tend to be independent of applicator orientation and give a distributed spray, they are limited in controlling the amount that is dispensed. In some devices contamination can result from contaminants being drawn into the applicator after some product has been dispensed. Accordingly, there remains a need for a fluid eye applicator better meeting the demands for dispensing ophthalmic medications in controller amounts.